42 Mr. A. H. Church 07i the Spontaneous Decomposition 



iu the mixture of the sulphomethylates of lime and barj'^ta*, are 

 thus well-crystaUized sulphate of lime, sulphate of baryta, water, 

 traces of au oily odorous body, with free sulphuric and sulpho- 

 mcthylic acids, the baryta salt of this last acid differing- in many 

 respects from the ordinary sulphomethylate of baryta although 

 isomeric with it ; I term it provisionally /3-sulphomethylate of 

 baryta. 



This baryta salt evidently corresponds in the methyle series 

 with the stable sulph?ethylate (parathionate) of Gerhardtf, ob- 

 tained from ordinary sulphasthylate of baryta by repeated ebul- 

 lition and neutralization with carbonate of baryta of its concen- 

 trated aqueous solution, and which more recently has been 

 identified by Berthelot l with the sulph.-ethylate of baryta obtained 

 by saturating with carbonate of baryta the mixture of 4 vols, 

 sulphuric acid and 1 vol. alcoliol, which has been employed in 

 making oleliant gas, or the solution of that gas iu oil of vitriol. 

 ]My opinion is also confirmed by the following experiments : — if 

 to a strong solution of ordinary sulphnethylate or sulphomethylate 

 of baryta a solution of protonitrate of mercury be added, a gray 

 or slaty precipitate occurs — with the parathionate of Gerhardt, 

 with the corresponding methyle compound which may be ob- 

 tained by the same method §, and with the /3-sulphomethylate 

 of baryta the precipitate is white. The two last-mentioned salts 

 are in fact in every respect identical. 



If the analytical results did not forbid such a view, it might 

 have been imagined that the modified or stable bai-yta salt was 

 really not the sulphomethylate, but the hyposulphomethylate of 

 baryta, for an aqueous solution of this latter salt, oi- indeed of 

 any of its analogues andhomologues, is quite unalterable. Sul- 

 phomethylic acid bears the same relation to hyposulphomethylic 

 acid as sulphophenic acid does to sulphobeuzolic acid, and it 

 may not be uninteresting to present in a tabular form some 

 relations between these two series. In the first column will be 

 found the formulae of a series of baryta salts, the aqueous solu- 

 tions of which are not alterable by ebullition — a series where the 

 proportion of sulphur to oxygen iu the dry salts is as 2 to 6 ; 



* For an account of the spontaneous decomposition of certain sulpho- 

 vinates, see Marchaud in the Journal fur Praktische Chemie, xhv. 122. 



t Compt. Rend, des travaux de Chimie, 1845, p. !/<). 



J Annales de Chimie et de Physique, 1856, p. 3U2. 



§ In 1853, at the suggestion and under the direction of Dr. Hofmann, I 

 prepared this salt and submitted it to a complete analysis. It is identical in 

 composition with ordinary sulphomethylate of baryta C^ IP Ba 2S0^ -)-2aq. 

 Although it is only recently that the metamorphoses of the sulphtcthylates 

 have been accurately studied, it would appear to have long been known 

 that aqueous solutions of the sulphomethylates undergo by ebullition similar 

 changes, and yield products exactly analogous to those of the jetbyle salts. 



